Subject matter

This TC aims to provide recommendations, in term of experimental tools, for the asphalt research and engineering community, concerning performance assessment of innovative bituminous materials. Innovation in the field of pavement construction is always facing difficulties in defining the “relevant” properties not only for the innovative product but also in comparison with conventional solutions. In order to facilitate sustainable implementations of new materials, new additives, new processes etc. it is necessary:

• To go towards intrinsic evaluation, relevant to the actual field performance. 
• To conduct studies at different scales: binder, mastics, mixture and pavement such as single layered structures.
• To understand bituminous materials as - multiphase materials:
  • A two phase materials: organic and mineral
  • A phase changing material with temperature, load and time of loading (from brittle elastic state to viscous state)
  • A multi phase structure in the binder
  • A multi-layer structure of the pavement
  • A phase changing material with ageing

Evaluation of one or several innovations for bituminous pavement materials will be proposed by following this working scheme. Three task groups (TG) will be proposed. Each TG will have its specific tasks focusing on one or several test methods: TG1 on the binder level, TG2 on the mix level and TG3 on the pavement structure level.

The first period (one or two year) will be dedicated mainly to experimental methods. During this period each TG will work independently. Then, in a second phase, common innovative materials, linked to actual sustainability issues, will be chosen and shared across TGs in order to have, finally, a complete evaluation of the innovative solutions.

The new TC will take advantage of the dynamism of the previous TC SIB (Testing and characterization of Sustainable Innovative Bituminous materials and systems). The constituted group of researchers and engineers has already proven that it is possible to make collaborative works. It is highly motivated to work on a new TC and agrees to attract more people.

TC PIM will be part of a RILEM TC ecosystem: TC CMB, TC MCD and TC RAP. TC PIM. Activities should not overlap with other TC subjects. Thus TC PIM will not deal with recycling issues, chemo-chemical analysis or cracking in pavement but rather benefit from these ongoing TC.

Terms of reference

The new TC will be active for 5 years. In order to achieve its goals, the TC intends as mentioned earlier to perform its work within three task groups (TG). Topics below are preliminary and might be subjected to changes in focus. The exact topics will be defined and proposed to the TC as soon as the TGs will be established.

TG1: Binders (L Porot)

- Testing of complex and combined binders (even going towards polymers, or compatibility of binders)

The asphalt pavement industry is facing new challenges on one hand towards an ineluctable shift for more sustainable and environmental friendly technologies and on the other hand a greater demand for performance based materials. This leads to new materials such as additives, polymers, solid particles to adjust the properties of conventional bituminous binder. However, the current specifications do not address completely the interface of new components in bitumen matrix. The TG will focus on compatibility and stability of modified bitumen in a wide range of conditions of use, low temperature, intermediate temperature, high temperature, elevated temperature, ageing etc.

TG2: Mixtures ( C Sauzéat)

- Low temperature performance of mixes

The aim of TG2 is to evaluate existing test methods (from simple performance tests to more advanced thermo-mechanical tests) and models for different types of mixtures. In order to better understand the behaviour of mixtures, it is necessary to consider their 3D mechanical properties. This is the reason why triaxial testing has received more and more attention in the last few years, as done during the last TC SIB with the characterization of the 3D viscoelastic linear behaviour of mixtures.

TG2 will focus on the low temperature performance of mixtures, which is responsible for failure of asphalt pavements, and often a key property for innovative mixtures. The Thermal Stress Restrained Specimen Test (TSRST) allows characterizing low temperature behaviour up to failure by coupling thermal and mechanical effects. Up to now, this test is mainly used to determine performance at failure, with uniaxial measurement. The objectives of the TG are improving the current TSRST method to obtain triaxial behaviour of mixtures, and analyzing the behaviour from small strain domain up to failure.

A first step will consist in a review of different laboratory procedure and equipment. Then, an interlaboratory TSRST campaign will be organised among participating research teams. At this step, devices equipped with triaxial strain measurement will be developed and used. Finally, developed devices and analysis methods could be applied to evaluate properties of innovative and sustainable materials, in common with other TGs.       

TG3: Pavement multilayer system (F Canestrari)

- Dynamic interlayer shear testing

The aim of TG3 activities is to focus on performance assessment at structural level of multilayer pavements. For this purpose, the interlayer characterization will be investigated through an innovative experimental methodology based on dynamic shear testing analysis.

Compared to the quasi-static laboratory tools currently used to analyse the interface shear properties mainly expressed in terms of shear strength, the dynamic shear testing approach should lead to more reliable performance parameters, strictly linked to the field behaviour of pavements under traffic loading.

In this sense, it would be helpful to understand the true bonding at the interface in terms of dynamic shear stiffness for better predicting the overall bearing capacity of multi-layered pavements. Moreover, also the fatigue resistance at the interface should be investigated to start giving a term of comparison with classic fatigue approaches based on tensile stress/strain. This latter aspect is fundamental to establish, for a given pavement structure, which is predominant between bottom-up cracking and slippage failure.

During the first phase of the TG3 activity, an inter-laboratory test on dynamic interlayer shear testing will be promoted involving several international research centres equipped with proper experimental testing facilities, in order to define appropriate testing protocols and meaningful parameters.

After analysis and interpretation of the experimental results collected in the first phase, a second phase will start aiming at the transfer of the previous outcome to the analysis of innovative and sustainable materials for a more reliable evaluation of their fruitful application in pavement engineering.

Objectives will be achieved by:

• Voluntary work of members who will be recruited from the actual TC 237 SIB (representing academics, industry and road research laboratories).
• One TC meeting per year (if possible in connection with other TCs related to bituminous materials)
• At least one additional annual meeting of each Task Group (TG)
• Reports and/or recommendations as well as publications of findings in Materials and Structures or other journals
• Presentation of findings during other international symposia and conferences in order to establish a lively link between RILEM and other organizations in that field
• Organization of seminars and workshops upon need
• Organization of 9th international symposium (follow-up SIB2015)
• Dissemination and Information on internet

Detailed working programme

Autumn 2016: Approval of new TC by TAC

during 2017: Individual meetings by TG’s; finalizing proposal of working plan; preparation of interlaboratory tests;

Autumn 2017: 1st Annual meeting of new TC: Discussion & approval of individual working plans, concepts and achievements, approval of workshops; evaluate data and place for 9th int. Symposium, define scientific committee

during 2018: Individual meetings by TG’s; follow individual working plan (e.g. literature reviews, material distribution, testing, first evaluations; plan & organize workshops)

Autumn 2018:2nd Annual meeting of new TC: Discussion & approval of individual working plans, concepts and achievements, finalize workshops; start planning 9th int. Symposium (1st announcement, call for papers)

during 2019: Individual meetings by TG’s; follow individual working plan (e.g. data evaluation, draft reports, first presentations and draft papers; carry out workshops)

Autumn 2019: 3rd Annual meeting of new TC: Discussion of progress & achievements; planning and approval of presentations, reports and papers, evaluate workshops; organizing 8th int. Symposium (acceptance of abstracts)

during 2020: Individual meetings by TG’s: follow individual working plan (e.g. data evaluation, draft reports, first presentations and draft papers)

Autumn 2020: 4th Annual meeting of new TC: Discussion of progress & achievements; planning and approval of presentations, papers, recommendations and reports; organizing 8th int. Symposium (acceptance of papers)

Spring 2021: 9th Int. Symposium (follow-up SIB09)

during 2021: Individual meetings by TG’s

Autumn 2021: 5th Annual meeting (Concluding); final report; presentation of the results during annual RILEM meeting